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Tianlai Collaboration Meeting

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Peter Timbie
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Albert and Reza are working on Fig. 16 (HI mass in tNCCSz as a function of redshift.) for the tNCCSz paper.   Responses to reviewer are nearly complete.  Discussion on June 16?

Special issue of "Universe".   Yougang has gotten several teams of authors to contribute papers about HI.

Wenxiu Yang gave an update on HI intensity mapping with FAST.  Her slides are attached below.  She is using "Powerbox" to create mock HI maps (10 of them) with foregrounds and studies the effect of PCA mode removal.  Very interesting discussion!   Reza suggested trying something different from PCA for cleaning (perhaps removing some Fourier modes).  Wenxiu reports using "arPLS"  (asymmetrically-reweighted Penalized Least Squares).

Yougang points out that at the low redshifts (z < 0.09) observed by FAST, it is able to measure the HI signal from individual galaxies with an HI mass threshold of 10^6 solar masses.  That's about 10 galaxies/ square degree, which is very high completeness.  Is this really intensity mapping?   Reza suggests looking at the Tianlai Dish Array low-z forecasting paper:  https://arxiv.org/abs/2205.06086  which describes operating in a similar limit of intensity mapping, where some "HI clumps" are expected.  

Xin Wang is discussing with Xuelei the SOC selection for the 21 cm Cosmology Workshop coming up in December.    The LOC has developed a website that is being approved.    The Workshop will include discussion of AI!  

Xin Wang has volunteered to present HI IM analyses in 2 weeks.

Peter postponed his review of Holder et al. for 2 weeks.   Albert has invited Gil Holder to present that work at Fermilab on Monday, June 22.

There are minutes attached to this event. Show them.
    • 8:00 AM → 8:02 AM
      Notes from last telecon (April 28) are available 2m
    • 8:02 AM → 8:22 AM
      POSTPONED! Discussion of "The Tau of Neutral Hydrogen: Increased CMB Optical Depth at Long Wavelengths" 20m

      Peter will review this recent paper by Holder et al: https://arxiv.org/abs/2605.22934 next time, on June 23.

      Speaker: Prof. Peter Timbie (UW - Madison Department of Physics)
    • 8:22 AM → 8:42 AM
      FAST HI IM - update 20m

      Wenxiu presented these slides, an update from her talk at previous Tianlai meeting.

      20260609_FAST_HIIM.pdf